Attack on Titan's final arc continues with the latest chapter of the series, and it's been building to what seems to be a complete apocalypse. After teasing for years that the rumbling would soon come to pass, the latest chapter of the series finally sees it come to pass. Previous chapters revealed that Eren's Attack Titan power gave him the surprise ability to not only look into the past -- as seen in the series -- but look into the future. Ever since he got a glimpse of what this is, he's been on a straight beeline towards it.
Chapter 123 finally reveals what Eren's really been fighting for all this time as he gathered the Yeagerists, betrayed his friends, partnered with Zeke and later betrayed him as well. After gaining command of the Founding Titan's power, he's now out for complete and total annihilation.
As the last chapter of the series revealed the past of Ymir, the very first Titan, this allowed Eren his way into her mind and heart. Winning her over, he gained full control of that power, and thus used it to awaken all of the Titans resting in the walls. Using this power, he contacts all the subjects of Ymir using a telepathy granted by the Coordinate Titan space.
He tells them that his goal is to protect the people of Paradis, and has unleashed the Titans from the walls surrounding the island. But because the world wants them dead, he will use the Titans to trample over every other land on the planet and will eliminated all lives outside of those living on the island.
This complete and total destruction has been hinted as his goal in the past as Eren wants to end the vicious cycle of the Titans overall, but while Zeke wanted to sterilize the people of Paradis, Eren was nothing but complete eradication and genocide of every other person on the Earth. With this goal, Eren has without a doubt cemented himself as the final antagonist of the series and now the series is heading for a questionable future before it all ends.
Attack on Titan was originally created by Hajime Isayama for Kodansha's Bessatsu Shonen Magazine in 2009. It's set in a world where the last remnants of humanity live within a walled city in order to escape the danger of the Titans, a race of giants monsters that eats humans. The lead character, Eren Yeager, ends up joining the military with his two childhood friends Mikasa and Armin after the Titans break through the wall and attack his hometown. Now Eren, Mikasa, and Armin must survive in a world where they not only have the Titans to fear, but the very humans they are trying to save. You can currently find the series streaming on Crunchyroll and Funimation.